Photoluminescent Tomography of Semiconductors by Two-Photon Confocal Microscopy Technique

The use of confocal microscopy with two-photon excitation of luminescence for studying bulk characteristics of semiconductors is discussed. The two-photon confocal microscopy technique is shown to possess high potential in recording of “planar” 2-D and “volumetric” 3-D photoluminescent images of semiconductor crystals, investigation of spatial distribution of the interband and defective-impurity luminescence, of non-equilibrium carrier lifetime, of interaction of radiative and non-radiative recombination centers with large-scale structure defects and of the influence of the surface effect on the above parameters. The planar maps of luminescence are observed deep inside the bulk of zinc selenide crystals to the depth up to 2 mm from the surface. The obtained maps are characterized by 1-mm spatial resolution and 3-nm spectral resolution. The applicability of two-photon confocal microscopy technique to monitoring of point defects in bulk crystal and investigation of their interaction with structural defects is discussed. The high potential of the method for studying specific behavior of grain boundaries in polycrystal materials is demonstrated.